1. Field of the Invention
The present invention relates to a device incorporated in an electrophotographic copier, facsimile transceiver, laser beam printer or similar image forming apparatus for controlling the supplement of a toner. More particularly, the present invention is concerned with a toner supplement control device for effecting the automatic supplement of a fresh toner from a toner case to a toner hopper only during a particular document image process mode operation in response to a toner near end signal from a toner near end sensor associated with the toner hopper.
2. Discussion of the Background
An image forming apparatus of the kind described is usually constructed such that when a toner stored in a toner hopper of a developing unit for developing a latent image electrostatically formed on a photoconductive element becomes short, a toner near end sensor detects the shortage. As the sensor generates a toner near end signal, a fresh toner is automatically supplemented from a toner casing storing it to the toner hopper. Stated another way, even when a copier has ended operating in a copy mode, a facsimile transceiver has ended operating in a receive mode and in a supervisory report output mode, or a laser beam printer has ended operating in a record mode, the fresh toner is immediately supplemented in response to the toner near end signal. This not only causes the operator of such an apparatus to feel uneasy but also generates unpleasant noise.
On the other hand, a toner magazine for feeding a fresh toner to the developing unit and a toner magazine for collecting a toner removed from a photoconductive element have customarily been mounted on the body of an image forming apparatus independently of each other. A disposable cleaner and toner magazine (CTM) is an implementation recently proposed to promote easy maintenance and reduce running cost. The CTM has the above-mentioned two toner magazines combined back-to-back in an integral construction. The prerequisite with the CTM is that whether or not a fresh toner is present in the CTM be determined at all times to see a time for replacement and to see if the magazine newly mounted is really new. However, since the CTM is a disposable unit, providing it with a toner sensor which is expensive for sensing a toner in the CTM is wasteful.